"use client";

import { createContext, useContext, useState, useEffect, ReactNode, useCallback } from "react";

interface User {
  id: number;
  email: string;
  role: string;
}

interface AuthState {
  user: User | null;
  accessToken: string | null;
  loading: boolean;
  login: (email: string, password: string) => Promise<void>;
  register: (email: string, password: string, inviteCode: string) => Promise<void>;
  logout: () => void;
  isLoggedIn: boolean;
  isAdmin: boolean;
}

const AuthContext = createContext<AuthState | undefined>(undefined);

const API_BASE = process.env.NEXT_PUBLIC_API_URL ?? "";

export function AuthProvider({ children }: { children: ReactNode }) {
  const [user, setUser] = useState<User | null>(null);
  const [accessToken, setAccessToken] = useState<string | null>(null);
  const [loading, setLoading] = useState(true);

  // init from localStorage
  useEffect(() => {
    const token = localStorage.getItem("access_token");
    const saved = localStorage.getItem("user");
    if (token && saved) {
      try {
        setAccessToken(token);
        setUser(JSON.parse(saved));
      } catch {}
    }
    setLoading(false);
  }, []);

  const saveAuth = (data: { access_token: string; refresh_token: string; user: User }) => {
    localStorage.setItem("access_token", data.access_token);
    localStorage.setItem("refresh_token", data.refresh_token);
    localStorage.setItem("user", JSON.stringify(data.user));
    setAccessToken(data.access_token);
    setUser(data.user);
  };

  const login = useCallback(async (email: string, password: string) => {
    const res = await fetch(`${API_BASE}/api/auth/login`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ email, password }),
    });
    if (!res.ok) {
      const err = await res.json().catch(() => ({}));
      throw new Error(err.detail || "Login failed");
    }
    const data = await res.json();
    saveAuth(data);
  }, []);

  const register = useCallback(async (email: string, password: string, inviteCode: string) => {
    const res = await fetch(`${API_BASE}/api/auth/register`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ email, password, invite_code: inviteCode }),
    });
    if (!res.ok) {
      const err = await res.json().catch(() => ({}));
      throw new Error(err.detail || "Registration failed");
    }
    const data = await res.json();
    saveAuth(data);
  }, []);

  const logout = useCallback(() => {
    localStorage.removeItem("access_token");
    localStorage.removeItem("refresh_token");
    localStorage.removeItem("user");
    setAccessToken(null);
    setUser(null);
  }, []);

  return (
    <AuthContext.Provider value={{
      user, accessToken, loading, login, register, logout,
      isLoggedIn: !!user, isAdmin: user?.role === "admin",
    }}>
      {children}
    </AuthContext.Provider>
  );
}

export function useAuth() {
  const ctx = useContext(AuthContext);
  if (!ctx) throw new Error("useAuth must be used within AuthProvider");
  return ctx;
}

// Authenticated fetch helper
export async function authFetch(path: string, options: RequestInit = {}): Promise<Response> {
  const token = localStorage.getItem("access_token");
  const headers = new Headers(options.headers);
  if (token) headers.set("Authorization", `Bearer ${token}`);
  
  let res = await fetch(`${API_BASE}${path}`, { ...options, headers });
  
  // try refresh on 401
  if (res.status === 401) {
    const refreshToken = localStorage.getItem("refresh_token");
    if (refreshToken) {
      const refreshRes = await fetch(`${API_BASE}/api/auth/refresh`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ refresh_token: refreshToken }),
      });
      if (refreshRes.ok) {
        const data = await refreshRes.json();
        localStorage.setItem("access_token", data.access_token);
        localStorage.setItem("refresh_token", data.refresh_token);
        headers.set("Authorization", `Bearer ${data.access_token}`);
        res = await fetch(`${API_BASE}${path}`, { ...options, headers });
      } else {
        // refresh failed, clear auth
        localStorage.removeItem("access_token");
        localStorage.removeItem("refresh_token");
        localStorage.removeItem("user");
      }
    }
  }
  
  return res;
}